1. Field of the Invention
The present invention relates to a sealer holding member for holding a sealer that shuts off the gap between a spiral-type membrane element and a vessel as well as a membrane element using the same. More particularly, the present invention relates to a sealer holding member capable of increasing the charged amount of the membrane (membrane leaves) of the membrane element as compared with a conventional one, as well as a membrane element using the same.
2. Description of the Related Art
From the past, a spiral-type separation membrane module is used for a variety of uses such as desalting of brine or sea water, production of ultrapure water, and processing of waste water. Referring to FIG. 9, a spiral-type separation membrane module has a structure such that a spiral-type separation membrane element E is housed in a pressure vessel 1, and the gap between the vessel 1 and the element E is shut off with an annular sealer 4 so as to allow a supplied feed 7 to flow efficiently into the element E. The feed that has flown into the element E is separated by a separation membrane while flowing toward the downstream side along the supply-side spacer of the element E. The permeate that has been permeated through the separation membrane flows along the permeation-side spacer and is collected into a water-collection tube 6. The membrane part of the element E is constructed with a wound body 2 of membrane leaves made of a lamination of the supply-side spacer, the separation membrane, and the permeation-side spacer.
FIG. 9 illustrates a state of an end portion when the vessel 1 is loaded with the element E and the feed 7 is supplied. The module has a mechanism such that the supplied feed 7 is shut off from the outside of the element E by the sealer 4, so that the total amount of the feed 7 flows into the inside of the element E. The module includes a sealer holding member 10 for holding the sealer 4 on the element E.
The aforesaid sealer 4 is held by the sealer holding member 10 that is attached to an end of the element E. Also, the sealer 4 is made of rubber or the like having a U-shaped or V-shaped cross section, and widens and extends toward the outside by a pressure at the time of receiving a water stream. In this state, the sealer 4 seals the gap between the element E and the vessel 1 (See, for example, Japanese Laid-open Patent Publication No. 11-76757/1999).
The sealer holding member 10 generally has a cylindrical portion 19 (skirt) for fitting an end of the wound body 2 constituting the membrane part, and has a structure such that an outer-covering member 5 of the element E can be fitted and bonded to the outer circumference of this cylindrical portion 19 (See, for example, Japanese Laid-open Patent Publication No. 2000-354742). However, with the structure such that the wound body 2 is fitted into the inside of the cylindrical portion 19, the diameter of the wound body 2 is limited, and there is a limit imposed upon the increase of the membrane area. Also, since the width of the wound body 2 in the axial direction is limited by the thickness of the sealer holding member 10, the thinner the sealer holding member 10 is, the more preferable it is. However, a certain thickness or more is required in view of forming a groove for holding the sealer 4 and the strength as a holding member.
On the other hand, in processes using a separation membrane, a cost down is demanded as a system, and one of the goals to be achieved is an increase in the housed membrane area per one element. For this purpose, it is necessary to increase the charged volume of the membrane leaves, so that there is a need to reduce the restriction imposed by the members put to use.